The ex-Tynecastle favourite - who is now plying his trade at Portuguese second division side Oriental - came up against the 18-year-old as he made his latest appearance for Sporting's B team on Sunday.

The Scotland Under-21 playmaker fired home a sensational volley to open the scoring in the Lion Cubs' 4-3 win.

It was the former Dundee United youngster's second goal for Sporting's second string since sealing his £3million move to Portugal.

The 18-year-old was included in Sporting's Champions League squad, but the man dubbed 'mini Messi' has yet to feature for Marco Silva's first team.

And while Aguiar claimed Gauld was a stand-out against bottom club Oriental, he warned the Scot he needs to improve further if he wants to take the next step.

Aguiar said: "I don't know if Ryan will ever become a top player. You can't say what will happen in the future.

"But he needs to improve more and more to make it into the first team at Sporting. You must work very hard to make it at the top level.

"At this time, right now, he still has work to do. He needs to show more if he wants to play for Sporting A."

SNS Group

Bruno Aguiar in action for Hearts in 2009

Gauld penned a six-year deal with the Portuguese champions following his summer switch from Tayside, while his contract even included a 60million euro release clause.

He opened the scoring for Sporting B on Sunday in the 28th-minute with a stunning 20-yard volley.

Internet footage of the strike has already been viewed over 1,250 times online.

Aguiar - who netted twice as Oriental mounted a late attempt at a comeback - said: "I don't watch a lot of the Segunda Liga matches so yesterday was the first time I've seen Ryan.

"I had read a bit in the newspaper before the match about this young kid coming over from Dundee United who was supposed to be the new Messi.

"And from what I saw yesterday you can see he has got quality.

"Sporting did not have a special game. The pitch was not so big, so it is not so easy to play. They created just four chances but scored them all.

"Ryan did well. He's young but when he has the ball he has a nice touch. He scored a fantastic goal. He was one of their best players on the day."